Our current and future research utilizes antibody technology for the generation of a large nave human Fab library in a newly designed phage display vector. We anticipate that this phage display library will become an important source for the generation of human monoclonal antibodies (mAbs) to a number of targets with relevance for hematologic malignancies. In FY05, we selected human mAb KYK-1 to human NKG2D from this library. NKG2D is expressed on NK cells which mediate the perhaps most important activity mechanism of antibodies, i.e. antibody-dependent cellular cytotoxicity (ADCC). In FY06, we further evolved KYK-1 through sequential affinity maturation based on phage display technology. The matured antibody now binds human NKG2D with subnanomolar affinity. We are currently evaluating KYK-1 (i) as diagnostic and therapeutic targeting device for NK-cell and T-cell lymphoma and leukemia, (ii) for the generation of bispecific antibodies designed to recruit NKG2D+ NK cells and NKG2D+ CD8+ T cells to the tumor site, and (iii) for interfering with autoimmune processes mediated by NK-cells and T-cells. Complementing our efforts for generating human monoclonal antibodies, we are continuing the mining of rabbit antibody repertoires by phage display. In particular, we have generated rabbit monoclonal antibodies selective for all three members of the Nogo receptor (NgR) family. NgR family members are cell surface proteins involved in the development, plasticity, and regeneration of the central nervous system. However, we have found recently that mRNAs of NgR family members are expressed also by peripheral blood mononuclear cells (PBMC). Our rabbit monoclonal antibodies will allow us to detect and define NgR family member expression on the surface of normal and malignant lymphocytes with a particular emphasis on T-cell and B-cell lymphoma and leukemia. Another aspect of our antibody engineering efforts is the development of new antibody conjugation technologies. In this area we are closely collaborating with chemists from the Laboratory of Medicinal Chemistry, CCR, NCI, NIH in Frederick, MD. In particular, we are exploring new technologies at the interface of monoclonal antibodies and small synthetic molecules, resulting in uniquely defined immunoconjugates in which the biological and chemical components are endowed with pharmacological advantages.